WDM Video Overlays on EFM Access Networks

Transcription

1 WDM Video Overlays on EFM Access Networks David Piehler Harmonic, Inc. Broadband Access Networks IEEE 802.3ah January 2002 meeting Raleigh, North Carolina 1

2 Main points of presentation Respond to reflector discussions on this subject. Review HFC technology and its application to all-fiber access networks Address technical concern areas Set the stage to provide details WDM video overlays have been widely deployed in P2P and P2MP topologies A WDM video overlay provides significant advantages for service providers 2

3 Analog video modulation Analog video information is encoded on discrete RF sub-carriers (channels): 6 MHz frequency For NTSC-80: channels range from 50 to 550 MHz For NTSC-110: channels range from 50 to 750 MHz For PAL-80: channels range from 50 to 870 MHz (with 8 MHz separation) IEEE 803.2ah meeting January 2002

4 The other QoS: Quality of Signal Transmission quality criteria: noise and distortion Carrier to noise ratio, CNR > 55 db for supertrunking > 47 Home for no snow Intermodulation distortion: Composite second order, CSO, and composite triple beat, CTB <- 65 dbc for supertrunking, < -54 for no lines also referred to as linearity IEEE 803.2ah meeting January 2002

5 CTB, CSO IEEE 803.2ah meeting January 2002

6 Classic HFC system: 1550 nm o/e/o or EDFA 1310 nm or 1550 nm o/e Coax + RF amps Fiber, EDFAs HEADEND HUB NODE HOME CNR 54 db 52 db 47 db CSO, CTB 65dBc 62 dbc 54 dbc fiber NODE to HOME link contributes 48.7 db CNR, 55 dbc CSO RF amplifiers produce most of the noise and distortion 6

7 Digital Video (and data) A typical modern CATV spectrum (cira 2002) 80 analog channels MHz 8 digital channels MHz 6 MHz Digital Channels: Contain downstream cable modem traffic and digital video Are 64- or 256-QAM modulated Are spectrally efficient A 6-MHz 64-QAM subcarrier carries 28 Mb/s of data Are much more robust than an analog channel Require much lower CNR, CSO, CTB MPEG compression + statistical multiplexing allows > 10 video channels to be delivered on a single 6 MHz RF subcarrier frequency 7

8 64-QAM data Bit-Error-Rate Bit-Error-Rate vs Distortion 1.00E E-02 BER 1.00E E-07 BER (RS) BER BER 1.00E E-06 BER (RS) BER (CNR 37) BER (CNR 33) 1.00E CNR (db) 1.00E Distortion 64-QAM With FEC, 10-9 BER can be achieved with CNR, distortion at 30 db(c) 8

9 SCM Video in FTTx Typical HFC deployments require (CNR/CSO/CTB) 55/65/65 optics Analog video in FTTH architecture requires 47/54/54 optics Digital (subcarrier multiplexed) video in FTTH architecture requires 30/30/30 to 40/40/40 optics (depends on modulation order, FEC and design margin) The all-fiber network and use of digital video make the optical requirements significantly less demanding compared to traditional HFC 9

10 Subcarrier multiplexing is the most efficient use of bandwidth OC48 Baseband digital: 2.5 Gb/s SCM:2.5Gb/s 80 6 MHz 64-QAM subcarriers MHz And the demodulation electronics (set top boxes, cable modems) are produced and used in commercial volume MHz 10

11 The video overlay - how? A broadcast video network can exist in the same physical plant as an existing P2P or P2MP EFM network by the use of WDM 11

12 Video PON w/ P2P EFM network 1550 nm analog Tx Edge Router EDFA GigE Tx/Rx EDFA GigE Tx/ Rx Switch 1xN split N x WDMs 1550/1310 WDM 1550/1310 WDM Video Rx 100baseFX Tx/Rx N 1310/1310 single fiber 100baseFX Tx/Rx Headend/CO hub/rt NIU A US ILEC has widely deployed this in a FTTC architecture (replace EFM with ATM) 12

13 Video PON with P2MP EFM network 1550 nm analog Tx EDFA EDFA 1xN split Edge Router PON OLT 1490 / 1310 Video Rx 1550/1490/1310 WDM 1550/1310/1490 WDM PON Tx/Rx PON MAC Headend/CO Hub/RT NIU 13

14 Review issues Solutions exist Technical issues Technical details can be discussed off-line or in future presentation Issues are Optical power for video receiver Optical isolation requirements for WDM at NIU Raman Crosstalk Double Rayleigh Scattering 14

15 Analog receivers require more power than digital receivers Carrier Noise = ( modulation index) 2 2 photo 2 B ( i + 2eI + (RIN) I ) e thermal photo photo I 15

16 Isolation requirements High power analog signal cannot leak into low power digital signal. Low power digital signal cannot leak into analog receiver and raise noise floor. 16

17 Raman Crosstalk 17

18 Double Rayleigh scattering Multipath interference creates noise floor which effect predominately the low frequency channels. MSOs always use angled connectors to reduce back reflections Telcos seem allergic to angled connectors Flat connectors work fine as long as proper craftsmanship is followed. Video overlays widely deployed with flat connectors. 18

19 Why does a video overlay make sense for service providers? The analog TV is the most common residential gateway in the world. Digital set top box volume driven by CATV applications - digital tiers and video on demand Digital SCM technology is amenable to HDTV Broadcast video is a proven market with proven revenue. But, it s a new / unfamiliar business for some Telcos 19

20 Video is the bandwidth hog Applications Example worst case Generated traffic, scenario DL (Mbps) TV & VoD 2 * HDTV (20Mbps/ch) TV (5Mbps/ch) Video ~2Mbps 2 Conferencing Web browsing <10Mbps 10 Streaming sound CD quality (200kbps) 0,2 Telephony ~100kbps 0,1 Approximate 62,3 total Source: Ericsson P2P 20

21 The big payoff Broadcast video ( analog or digital ) is very bandwidth efficient Switched video is a bandwidth hog. If video is the dominant bandwidth application, use of an overlay can relax bandwidth requirements on an EFM network, enabling lower cost more splits more distance 21

22 Wavelength Allocation nm (G.983.3) for video overlay is fine. However, realize that a video overlay may use more than one video wavelength to Enable optical narrowcasting for targeted video services segment the video broadcast Increase the CNR The nm band will accommodate multiple wavelengths 22

23 Optical Narrowcasting INTERNET HEADEND 8 db Link at 1550 nm Two PONS in One HUB Cable Modem Digital Set-Top Analog TV RESIDENCE Cable Modem Termination Directed Digital Video Tx λ 1 Tx λ 2 Tx λ 3 1x8 WDM EDFA 1x8 WDM λ 3 WDM WDM WDM Split Split Split NODE NODE Broadcast Video external mod MHz λ B Tx λ 8 Broadcast Tx λ B EDFA 1x N splitter WDM Split NODE NODE 23